1. Field of the Invention
The present invention relates to a oneway valve and, more particularly, to a oneway valve for an automatically inflatable air cushion.
2. Description of the Related Art
A conventional air nozzle for an automatically inflatable air cushion in accordance with the prior art shown in FIG. 7 comprises a mounting seat 30 mounted on an automatically inflatable air cushion 31 containing a packing 311, a connecting pipe 10 having a first end mounted on the mounting seat 30 by ratchet teeth 16 and limit bosses 15, a mediate portion formed with an outer thread 14 and a second end formed with a mounting portion 12 having an inside formed with an annular passage 13 connected to the mounting seat 30, a control cap 20 rotatably mounted on the connecting pipe 10 and having an inside formed with an inner thread 24 screwed onto the outer thread 14 of the connecting pipe 10 and an end face 21 provided with a protruding seal portion 23 that is movable to seal the passage 13 of the connecting pipe 10, and a gasket 11 mounted in the passage 13 of the connecting pipe 10 to press the seal portion 23 of the control cap 20 when the seal portion 23 of the control cap 20 is inserted into the passage 13 of the connecting pipe 10. The connecting pipe 10 has an inside formed with an air chamber 101 connected between the mounting seat 30 and the passage 13. The control cap 20 has an inside formed with an air channel 25 connected to the passage 13 of the connecting pipe 10 when the seal portion 23 of the control cap 20 is detached from the passage 13 of the connecting pipe 10. The end face 21 of the control cap 20 has a peripheral wall formed with a plurality of air vents 22 connected to the air channel 25.
In practice, the inner thread 24 of the control cap 20 is screwed onto the outer thread 14 of the connecting pipe 10, so that when the control cap 20 is rotated relative to the connecting pipe 10, the seal portion 23 of the control cap 20 is movable relative to the passage 13 of the connecting pipe 10. Thus, the seal portion 23 of the control cap 20 is movable to detach from the passage 13 of the connecting pipe 10 to open a connection between the air channel 25 of the control cap 20 and the passage 13 of the connecting pipe 10, so that an air from the ambient environment is in turn introduced through the air vents 22 of the control cap 20, the air channel 25 of the control cap 20, the passage 13 of the connecting pipe 10, the air chamber 101 of the connecting pipe 10 and the mounting seat 30 into the automatically inflatable air cushion 31 so as to inflate the automatically inflatable air cushion 31 automatically. On the contrary, the seal portion 23 of the control cap 20 is movable to seal the passage 13 of the connecting pipe 10 to interrupt the connection between the air channel 25 of the control cap 20 and the passage 13 of the connecting pipe 10, so as to stop the air flow into the automatically inflatable air cushion 31.
However, the user needs to rotate the control cap 20 successively to move the seal portion 23 of the control cap 20 to detach from the passage 13 of the connecting pipe 10 so as to open the air flow or to move the seal portion 23 of the control cap 20 to seal the passage 13 of the connecting pipe 10 so as to close the air flow, thereby causing inconvenience to the user when operating the air nozzle. In addition, after inflation of the automatically inflatable air cushion 31, the user needs to rotate the control cap 20 successively to move the seal portion 23 of the control cap 20 to seal the passage 13 of the connecting pipe 10 to close the air flow, so that the air easily leaks from the automatically inflatable air cushion 31 before the seal portion 23 of the control cap 20 reaches and seals the passage 13 of the connecting pipe 10, thereby decreasing the inflating effect.